Pyrogen or endotoxin (LAL) testing is required for parenteral drugs. Classical endotoxin assays cannot be used to test the endotoxin content of Aluminium salts. The endotoxin control added to the product is not recovered due to its property of interacting with the aluminium salt. Assay validity criteria require recovery and the ability to measure the control endotoxin in bulk aluminium concentrations. Given this interaction it is generally considered that the standard endotoxin tests are unsuitable for endotoxin testing in aluminium salt adjuvants. The only test that is suitable for determining endotoxin is the rabbit pyrogen test which involves injection of the aluminium salt into rabbits. Improved methods are required.